flash加载外部图片等比缩放类(as3)

package com.sunxinzhe.display { import flash.display.Bitmap; import flash.display.BitmapData; import flash.display.DisplayObject; import flash.display.IBitmapDrawable; import flash.geom.Matrix; import flash.geom.Rectangle; /** * ...图像数据处理工具 */ public class BitmapUtil { /** * 获取按指定尺寸等比例缩放+居中的截图 * @param target 目标对象 * @param tarW 目标尺寸(宽) * @param tarH 目标尺寸(高) * @param full 是否显示图片全貌 * @return */ public static function getZoomDraw(target:DisplayObject, tarW:int, tarH:int,full:Boolean=true):BitmapData { //获取显示对象矩形范围 var rect:Rectangle = target.getBounds(target); //计算出应当缩放的比例 var perw = tarW / rect.width; var perh = tarH / rect.height; var scale = full?((perw <= perh)?perw:perh):((perw <= perh)?perh:perw); //计算缩放后与规定尺寸之间的偏移量 var offerW = (tarW - rect.width * scale) / 2; var offerH = (tarH - rect.height * scale) / 2; //开始绘制快照（这里透明参数是false,是方便观察效果，实际应用可改为true) var bmd:BitmapData = new BitmapData(tarW, tarH, false, 0); var matrix:Matrix = new Matrix(); matrix.scale(scale, scale); matrix.translate( offerW, offerH); bmd.draw(target, matrix); //如果是bitmap对象，释放位图资源 if (target is Bitmap) (target as Bitmap).bitmapData.dispose(); //返回截图数据 return bmd; } } }